In order to understand this condition, it is important to understand the anatomy and function of the foot. Please read Foot Pain Info‘s section on basic foot anatomy. For additional background information on the biomechanics of the foot please read Foot Pain Info‘s section on basic foot and ankle biomechanics.

Sesamoid Bones of the Foot

What is a sesamoid bone?

A sesamoid bone is a bone that found in the substance of a tendon. Tendons are “rope like” structures that connect muscles to bone.

Where are the sesamoid bones located in the foot?

In the foot there is a small muscle called the flexor hallucis brevis. The tendons of this muscle run along the bottom of the foot, under the head of the first metatarsal bone, and attach to the small bone of the big toe. In the foot there are two main sesamoid bones, an inner (medial or tibial) sesamoid and an outer (lateral or fibular) sesamoid. These sesamoid bones are located under the head of the first metatarsal bone, in the tendons of the flexor hallucis brevis muscle.

What is sesamoiditis?

Sesamoiditis is the term used to describe irritation (inflammation) of the tendons and tissues surrounding the sesamoid bones of the foot. Sesamoiditis usually affects the medial, more than the lateral, sesamoid.

What does sesamoiditis feel like?

The pain from sesamoiditis is usually felt under the head of the first metatarsal bone. Tenderness and sometimes swelling can also be present in this area. Pain is often made worse by bending the big toe up, at the MTP joint and pressing on the affected sesamoid bone.

What causes sesamoiditis?

Sesamoiditis usually develops as a result of overuse. Activities such as jumping, running, walking or even prolonged standing can cause undue stress on the sesamoid bones and their surrounding structures. This in turn leads to the development of microscopic tears in the tendons or tissues around the sesamoid bones resulting in inflammation and pain. Poor flexibility of the calf muscles and of the Achilles tendon, overpronation (feet rolled in), high arched feet and inappropriate footwear some of the other factors that can cause sesamoiditis.

Can sesamoiditis be detected on X-rays?

Sesamoiditis cannot be seen on regular x-rays. However, x-rays can detect a bipartite sesamoid bone (the bone appears as two separate pieces on x-rays and this can be confused with a fracture) or wear and tear arthritis (osteoarthritis) between the sesamoid bones and the first metatarsal bone. Other tests such as bone scans or MRI’s are usually ordered if the diagnosis is unclear or if a condition other than sesamoiditis is suspected (see the paragraph on special considerations).

What is the treatment for sesamoiditis?

The treatment of sesamoiditis should be individualized. The most important first steps in the treatment (and prevention) of sesamoiditis are to reduce aggravating activities and to wear proper shoes. Further treatment may include icing to decrease pain around the sesamoid bones, stretching and strengthening exercises, shoe orthotics or medications. Complete rest with a removable cast or a cortisone injection may be required to reduce inflammation and pain. Surgery is rarely necessary for sesamoiditis.

Are there any special considerations for sesamoiditis?

The sesamoid bones can develop stress fractures or they can develop complete fractures. Sometimes the pain from bunions can be confused with sesamoiditis. These conditions may require different treatment and investigations than sesamoiditis.

What other information is available on sesamoiditis?

Foot Pain Info ‘s links section has additional information on this topic. Links have been provided to other websites as well as online medical journals. Visit Joint Pain Info for information on other joint injuries and problems.